1. Field of the Invention
The present invention relates generally to papermaking conveyor belts or "wires" and, more particularly, to a papermaking wire comprising a weave pattern for a smoother paper and more durable wire.
2. Description of the Prior Art
For the manufacturing of paper, conveyor belts are used to feed the pulp suspension to the press equipment. These belts are termed "papermaking wires" and are formed from woven strands of "yarn" or "wire".
The pulp suspension is dried while being transported on the papermaking wire to the press equipment. In order to aid the pulp drying process, the papermaking wire must be permeable, therefore, the weave pattern of the wire is important.
A longitudinal yarn or wire is called a warp yarn. A horizontal or crossweave is called a weft yarn. The weave pattern is formed from the interweaving to warp and weft yarns. A "knuckle" is formed where a warp yarn passes over or under one weft yarn or where a weft yarn passes over or under one warp yarn. A "float" is where a warp yarn travels over or under two or more weft yarns or a weft yarn passes over or under two or more warp yarns.
The wire has an upper face which comes in contact with the pulp suspension, the paper side, and a lower face which comes in contact with the conveyor rollers, the machine side. The running side refers to the weft threads on the machine side. Thus, the wire must be permeable to aid in the drying of the pulp suspension as it travels to the paper press, and durable to withstand the wear from the conveyor rollers. The weave pattern of the wire, therefore, is directly related to the permeability and durability of the wire.
To create a permeable wire, and a smoother paper, it is desirable to have floats on the paper side of the weave pattern. To create durability it is also desirable to have floats on the machine side as the knuckles protrude from the wire and wear against the conveyor rollers. However, if a weave has too many floats on either the paper side or machine side the wire will tend to curve, creating a rolled paper edge or thinned paper edge respective of which side the wire is curving towards.
In order to maintain maximum permeability and durability, it has been found necessary to increase the number of meshes, or open spaces in the weave, per square centimeter area of the wire. Increasing the meshes simultaneously creates a uniform fiber while decreasing the potential markings caused by the wire in the drying pulp.
Increasing the amount of meshes has resulted in refining the wire or yarns. Such refining, however, is limited where decreasing the diameter of the wire directly decreases the durability of the wire. Therefore, a trade-off must be made between the smoothness of the paper and the useful life of the papermaking wire.